Re: [PATCH 5/5] Notify nested hypervisor of lost event injections

[Joerg Roedel <joro@8bytes.org>]

On Fri, Sep 18, 2009 at 03:00:32PM +0200, Alexander Graf wrote:
> Normally when event_inj is valid the host CPU would write the contents to
> exit_int_info, so the hypervisor knows that the event wasn't injected.
> 
> We failed to do so so far, so let's model closer to the CPU.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>

Acked-by: Joerg Roedel <joerg.roedel@amd.com>

The commit-message does not state this explicitly, but this patch fixes
a real bug with lost interrupts in nested svm.

> ---
>  arch/x86/kvm/svm.c |   16 ++++++++++++++++
>  1 files changed, 16 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 12ec8ee..75e3d75 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1643,6 +1643,22 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
>  	nested_vmcb->control.exit_info_2       = vmcb->control.exit_info_2;
>  	nested_vmcb->control.exit_int_info     = vmcb->control.exit_int_info;
>  	nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err;
> +
> +	/*
> +	 * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have
> +	 * to make sure that we do not lose injected events. So check event_inj
> +	 * here and copy it to exit_int_info if it is valid.
> +	 * exit_int_info and event_inj can't be both valid because the below
> +	 * case only happens on a VMRUN instruction intercept which has not
> +	 * valid exit_int_info set.
> +	 */
> +	if (vmcb->control.event_inj & SVM_EVTINJ_VALID) {
> +		struct vmcb_control_area *nc = &nested_vmcb->control;
> +
> +		nc->exit_int_info     = vmcb->control.event_inj;
> +		nc->exit_int_info_err = vmcb->control.event_inj_err;
> +	}
> +
>  	nested_vmcb->control.tlb_ctl           = 0;
>  	nested_vmcb->control.event_inj         = 0;
>  	nested_vmcb->control.event_inj_err     = 0;
> -- 
> 1.6.0.2
> 
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